As the driving force of the electric vehicle is supplied by use of a battery, the endurance mileage of the electric vehicle is limited, resulting in that it is very easy that the electric vehicle broke down due to power exhaustion. To this end, it is needed to evaluate battery power and driving mileage of the electric vehicle. When the driving mileage of the electric vehicle is evaluated in the prior art, generally, SOC of a vehicle-mounted battery is firstly estimated (state of charge evaluation) so as to obtain the condition of the power stored by the vehicle, and then the remaining driving mileage is roughly estimated according to the average energy consumption level of the vehicle. In this method, it is not enough accurate to calculate the power consumption of the attachments, and the current remaining driving mileage is only estimated. As the consumption of the battery power at a lower level is faster, and the road condition of the city is complex, the power has been exhausted in the case that the remaining driving mileage is not reached so that the vehicle broke down on the road, which brings great inconvenience to the user.